1 . Field of the Invention
The present invention relates to an optical tomographic imaging apparatus, an image processing apparatus, and an optical tomographic image display method.
2 . Description of the Related Art
Currently, there are various types of ophthalmological instruments using an optical instrument. For instance, as an optical instrument for observing an eye, there are used various instruments such as an anterior ocular segment imaging instrument, a fundus camera, and a confocal laser scanning ophthalmoscope (scanning laser ophthalmoscope: SLO). In particular, an optical tomographic imaging apparatus, which performs optical coherence tomography (OCT) utilizing an interference phenomenon of multi-wavelength light, is an apparatus capable of obtaining a tomographic image of a sample with high resolution. For this reason, the optical tomographic imaging apparatus is becoming an indispensable apparatus as an ophthalmological instrument for a specialist of retina in the outpatient field. In addition, the optical tomographic imaging apparatus is used not only for ophthalmologic use but also for an endoscope or the like. This apparatus is hereinafter referred to as “OCT apparatus”. The OCT apparatus is widely used for acquiring a tomographic image of a retina of a fundus of an eye to be inspected or a tomographic image of an anterior ocular segment such as a cornea in ophthalmologic diagnosis or the like.
The OCT apparatus is capable of spliting measuring light having low coherence into reference light and measuring light, and irradiating an object to be inspected with the measuring light to cause return light from the object to be inspected to interfere with the reference light, to thereby measure a layer of the object to be inspected. Further, the OCT apparatus can obtain a tomographic image with high resolution by scanning the sample with the measuring light. Further, the OCT apparatus one-dimensionally scans a specific area with the measuring light so as to acquire a two-dimensional tomographic image. Further, the one-dimensional scan for acquiring the two-dimensional tomographic image is repeated while shifting the position, to thereby acquire a three-dimensional image.
Here, in the ophthalmologic diagnosis, an operator may refer to data of images photographed in the past for detailed diagnosis of a lesion of the eye to be inspected or its variation with time. In addition, the operator may refer to photography data in the past and reads the photography condition for performing the photography in the same composition and the same condition (follow-up photography) in order to study variation with time of individual lesions. Therefore, it is desired to display the data of images photographed in the past in a display form such that the data can be easily looked up.
In contrast, Japanese Patent Application Laid-Open No. 2006-092201 discloses a three-dimensional image processing apparatus for medical images, in which multiple pieces of three-dimensional data are listed as thumbnail images that are processed by rendering for two-dimensional image projection. In addition, Japanese Patent Application Laid-Open No. 2012-045225 discloses an image processing apparatus for ophthalmologic use, which selects one tomographic image from three-dimensional data and displays the selected image as a thumbnail image. The thumbnail image as used herein means a low resolution image in which the number of horizontal and vertical pixels is reduced so that its pattern can be seen at a glance.
However, it may be easier for the operator to grasp a feature and to retrieve desired data if an image parameter of the thumbnail image in the display is adjusted to be an optimal value for the operator.